The Sound of the Big Bang

Temperature variations of the cosmic background radiation as
measured by
Planck.
Red indicates high temperature and blue low temperature.

I'm a Professor
Emeritus of Physics at the University of
Washington in Seattle. About 10
years ago, when the WMAP data on the cosmic microwave background (CMB) became
available, I did a Mathematica calculation to produce "the sound of the
Big Bang", I wrote an Alternate View column published in Analog Science
Fiction/Fact Magazine about it (see
AV-122 in the May-2003 issue of Analog), and I put it online,
where it received a great deal of attention. I have decided to do the same
thing with the new data from the ESA's Planck Mission analysis of the CMB, which
analyzes the temperature variations of the cosmic microwave background into
angular frequency components or multipoles. The new frequency spectrum
goes to much higher frequencies than did the WMAP analysis, and therefore offers
a more "high-fidelity" rendition of the Sound of the Big Bang. The Planck
multipole spectrum looks like this:

It was not as easy to
use the data this time because, while the WMAP group provided an easy-to-find
table of multipole strengths from their analysis, the Planck group has set up an
arcane system of data archives and ".fit" files that, after several hours of
effort, I was not able to penetrate to obtain the data I wanted. Finally,
with the help of Dr. Richard Gass of the University of Cincinnati, who provided
a sample notebook and advised upgrading from Mathematica 8 to Mathematica 9, I
was able to extract the Planck multipole data, which is plotted above and
included below as a .txt file.

The Sound of the Big Bang simulation
includes three important effects: (1) The multiply peaked frequency spectrum
measured by Planck is made into a single sound wave (monaural, not stereo) by
the process described above; (2) According to the Planck analysis, the emission
profile of the cosmic background radiation peaked at 379,000 years and dropped
to 60% intensity at 110,000 years before and after the peak emission time. The
simulation represents the first 760,000 years of evolution of the universe, as
the emitted CBR rises and falls in intensity following the Planck profile; (3)
The universe was expanding and becoming more of a "bass instrument" while the
cosmic background radiation was being emitted. To put it another way, the
expanding universe "stretches" the sound wavelengths and thereby lowers their
frequencies. To account for this effect, the program shifts the waves downward
in frequency to follow the expansion in the first 760 thousand years of the
universe. How fast the universe initially expanded depends on what cosmological
model is used. I decided to follow the predictions of the flat-space
Robertson-Walker metric with zero cosmological constant. That model predicts
that the radius of the universe grows as time to the 2/3 power (R ~ t2/3).
Therefore, instead of the component sine waves varying as (frequency
´ time), they vary
as (frequency ´ time1/3)
to implement the cosmological Doppler shift. The sound frequencies used in the
simulation must be scaled upward by a huge factor (about 10 to the 26 power) to
match the response of the human ear, because the actual Big Bang frequencies,
which had wavelengths on the order of a fraction of the size of the universe,
were far too low to be heard by humans (even had any been around).

I made .wav files from the simulation
with playing-time duration of 20, 50, 100, 200, and 500 seconds. These may
be downloaded here, along with the Mathematica notebook that produced the
.wav files and the data file of the Planck multipole spectrum:

I recommend the 100
second version, but you can choose for yourself. These audio files can be
downloaded and used for any purpose, provided the text "(c) John G. Cramer -
2013" is used in text related to the file. References to my website, my
Analog Columns, and my two hard science fiction novels Twistor and
Einstein's Bridge are also encouraged and would be appreciated.